Small tools and instruments are extremely useful for performing work in small, crowded or otherwise hard to reach spaces. For example, during surgery a surgeon frequently uses a battery operated cautery to cauterize bleeding blood vessels. One such cautery resembles a penlight flashlight with a heating element extending from one end. When bleeding occurs during surgery, the surgeon lays down (or hands to a nurse) whatever instrument the surgeon has been using and asks a nurse for the cautery. The nurse picks up the cautery, removes a protective cap and hands the cautery to the surgeon. The surgeon takes the cautery and positions it in his or her hand such that the on-off switch (generally a momentary contact push switch) is properly located under the finger or thumb the surgeon uses to operate the switch. When cauterization is completed, the surgeon hands the cautery back to the nurse, picks up (or is handed) and positions another instrument in his or her hand and continues with the surgery. Simultaneously, the nurse replaces the protective cap over the cautery tip and places the unit on a stand, ready for its next use.
A significant drawback to such a device is that the exchange between nurse and surgeon may occur many times during surgery, a time consuming procedure which, because of the extra steps and personnel involved, can slow down or interrupt the flow of the surgery. Alternatively, if the surgeon lays the cautery down on the sterile surgical field without handing it back to the nurse, the hot tip may burn a hole in whatever it touches, such as paper draping material or a surgical glove, thus breaking the sterile field. And, the cylindrical shape of the cautery makes it prone to rolling and the instrument may roll onto the floor. An additional disadvantage is that the use of such a cautery is limited by the life of its non-replaceable, internal batteries. If the surgery is a long one or requires cauterization of many bleeding blood vessels, the batteries in the cautery may be exhausted before the surgery is completed, thus necessitating obtaining a replacement unit.
Other medical devices, such as flashlights and suction apparatus, have some of the same drawbacks as the portable cautery just described. That is, they may require time consuming handling by various personnel and may require additional manipulation by the surgeon before they can be used. Furthermore, the limited battery life of some instruments can limit their usefulness, especially during long procedures. Similarly, small tools and instruments used by non-medical personnel also have some of the same drawbacks. For example, small flashlights, soldering guns, blowers and vacuums are used by jewelers, electricians, mechanics and model builders and require similar handling and manipulation as the small medical devices.
It is known to use switches to control electrical devices, such as medical instruments. Some electrosurgical instruments, such as those disclosed in U.S. Pat. Nos. 4,552,143 by Lottick and 4,041,952 by Morrison, Jr. et al., employ switches which are mounted on the side of the instrument. To operate such an instrument, the surgeon holding the instrument presses and releases a button to activate and deactivate the instrument.
Other instruments employ switches located remote from the instrument. U.S. Pat. No. 702,472 by Pignolet discloses surgical forceps connected to a source of electric energy. The tissue to be cauterized is grasped and the unit is activated by a remote switch allowing current to flow to a heating element in one or both of the forcep jaws. When cauterization is complete, the tissue is released and the switch turned off. U.S. Pat. No. 3,845,771 by Vise discloses an electrosurgical glove which has an electrical contact pad on the outside surface of at least one of the digits of the glove. A lead embedded in the glove is connected to a current or radio frequency energy source. To use, the wearer of the glove picks up an electrically conductive instrument making sure that the contact pad on the glove makes proper contact with the instrument. The user turns on a separate switch to provide current or radio frequency energy from the source through the glove to the instrument.
Still other electrosurgical devices have integrated switches in which a mechanical operation simultaneously activates or deactivates an electrical circuit. U.S. Pat. No. 2,012,937 by Beuoy discloses Y-shaped electrical caponizing forceps having a cauterizing bar extending across the forked end of the forceps. The forceps are connected to an electrical power source and, when the two arms of the forceps are squeezed together, electrical contact is made sending current to the cauterizing bar. When the forceps are released, the cauterizing bar turns off.
Consequently, it is desirable for small instruments and tools to be easy to activate and deactivate and be readily available without necessitating extra steps by the user or support personnel. It is further desirable that medical instruments be quickly available but without risk to the sterile surgical field, that they be light weight and that their battery life be extendable.